Letters Covering letter to copies of T.Kunitachi's and T.Yoneda's paper and an addendum to it specifying the place of the paper's presentation. Date: 22.11.1979- 12.12.1979 Original document language: English Authors: Tsutomu Kunitachi Organizations: IFIP Persons: Tomio Yoneda Addressee: Andrei Petrovich Ershov